Monitoring the effective population size of a brown bear (Ursus arctos) population using new single-sample approaches

The effective population size (Ne) could be the ideal parameter for monitoring populations of conservation concern as it conveniently summarizes both the evolutionary potential of the population and its sensitivity to genetic stochasticity. However, tracing its change through time is difficult in natural populations. We applied four new methods for estimating Ne from a single sample of genotypes to trace temporal change in Ne for bears in the Northern Dinaric Mountains. We genotyped 510 bears using 20 microsatellite loci, and determined their age. The samples were organized into cohorts with regard to the year when the animals were born and yearly samples with age categories for every year when they were alive. We used the Estimator by Parentage Assignment (EPA) to directly estimate both Ne and generation interval for each yearly sample. For cohorts, we estimated the effective number of breeders (Nb) using Linkage Disequilibrium, Sibship Assignment and Approximate Bayesian Computation m...